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Composition of Steel,


Generally, then, wrought iron is tough, and more capable of
resisting vibration than cast iron, its fibrous character giving it
also a distinct advantage in the direction of the fibre, which
property may be made use of by judicious crossing in the opera-
tions of piling and re-heating the iron after puddling.

The best forgings are usually made by the piling of wrought
iron scrap.

(3 and 4.) Steel is intermediate in composition between
-wrought and cast iron, thus:

Cast iron may have  2-2   to 5    percent, of carbon.
Steel (for casting)        -3      17              ,,

Steel (for forging)       -25 ,,1-5               ,,

Wrought iron             'o        -25             ,,

It will be clear, however, that the exact limits between which
we   may   call   the   substance    steel,3
without intruding on either wrought or

- cast iron, are very difficult to define, so
that we may have steel which is almost

. as brittle as cast iron, or we may have
it on the other hand nearly as soft as
wrought iron.

Although steel has an intermediate

 composition, it has not, as we might
. expect, an intermediate tenacity or use,

' but is stronger even than wrought iron
. and consequently more useful. It never has quite the toughness
. of the best wrought iron, though approaching it closely with
...mechanical treatment; it is always more homogeneous,

It will also be readily           that, as           is intermediate In